Dividing groove forming device, and dividing groove forming method

ABSTRACT

A dividing groove forming device includes: a first cutter including a plurality of first rotary blades; a second cutter including a plurality of second rotary blades; a first rotation drive unit for rotationally driving the first cutter; a second rotation drive unit for rotationally driving the second cutter; a cutter support unit; and a phase adjustment unit. The cutter support unit supports the first cutter and the second cutter such that the first and second cutters are radially opposed to each other so that rotation axes of the first and second cutters are parallel to each other. The phase adjustment unit adjusts a phase of at least one of the first cutter and the second cutter such that the first rotary blades and the second rotary blades are opposed to each other in an opposing area in which the first cutter and the second cutter are opposed to each other.

TECHNICAL FIELD

The present invention relates to a dividing groove forming device and adividing groove forming method for forming dividing grooves for dividinga substrate at corresponding positions on one surface and the othersurface of the substrate.

BACKGROUND ART

Heretofore, the following method is known as a method for manufacturinga substrate of an electric device and the like. Specifically, aplurality of substrates are collectively built in one substrate.Dividing grooves are formed from front and back surfaces between unitsubstrates in the substrate. The substrate is divided into a pluralityof unit substrates by the dividing grooves. Patent Literature 1discloses an example of a dividing groove forming device used for such asubstrate manufacturing method. This dividing groove forming deviceincludes two cutters each including a plurality of rotary blades.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application PublicationNo. 2012-86353

In the related art disclosed in Patent Literature 1, the positionalrelationship between the rotary blades of the two cutters was not takeninto consideration at all. Accordingly, there is a possibility that, inan opposing area in which the two cutters are opposed to each other, thepositions of the rotary blades can deviate from their opposedoppositions in most of a rotational driving period. Therefore, there isa possibility that a waviness phenomenon occurs on the substrate.

The waviness phenomenon will be described in detail later. FIG. 6 is afront view illustrating a positional relationship between a first rotaryblade 2 a and a second rotary blade 3 a in a dividing groove formingdevice 1 of the related art which is the same type of theabove-mentioned related art. Referring to FIG. 6, the first rotary blade2 a of a first cutter 2 and the second rotary blade 3 a of a secondcutter 3 deviate from their opposing positions. Accordingly, a firstportion 4 a of a substrate 4 with which the first rotary blade 2 a isbrought into contact is pressed downward and deformed. A second portion4 b of the substrate 4 with which the second rotary blade 3 a is broughtinto contact is pressed upward and deformed. As a result, a wavinessphenomenon occurs on the substrate 4, so that the depth of the dividinggrooves formed in the first rotary blade 2 a and the second rotary blade3 a becomes non-uniform. Further, if the waviness width increases, thedividing grooves themselves may not be formed, or the dividing groovesmay penetrate through the substrate 4. If the dividing grooves penetratethrough the substrate 4, the strength of the substrate 4 is considerablylowered, so that a malfunction occurs in post processing, and at worst,the substrate may crack during formation of the dividing grooves.

SUMMARY OF INVENTION

The present invention has been made in view of the above-mentionedproblems. An object of the present invention is to provide a dividinggroove forming device and a dividing groove forming method which arecapable of forming dividing grooves accurately at a constant depth.

In order to achieve the above-described object, a feature of a dividinggroove forming device according to the present invention is that thedividing groove forming device is for simultaneously forming a firstdividing groove and a second dividing groove for dividing a substrate,the first dividing groove and the second dividing groove beingrespectively formed at corresponding positions on one surface and theother surface of the substrate, and the dividing groove forming deviceincludes: a first cutter for forming the first dividing groove, thefirst cutter including a plurality of first rotary blades; a secondcutter for forming the second dividing groove, the second cutterincluding a plurality of second rotary blades; a first rotation driveunit for rotationally driving the first cutter; a second rotation driveunit for rotationally driving the second cutter; a cutter support unitfor supporting the first cutter and the second cutter in such a mannerthat the first cutter and the second cutter are radially opposed to eachother so that rotation axes of the first cutter and the second cutterare parallel to each other; and a phase adjustment unit for adjusting aphase of at least one of the first cutter and the second cutter in sucha manner that the first rotary blades and the second rotary blades areopposed to each other in an opposing area in which the first cutter andthe second cutter are opposed to each other.

In this structure, the first rotary blades and the second rotary bladesare opposed to each other in an opposing area in which the first cutterand the second cutter are opposed to each other. Accordingly, a wavinessphenomenon can be prevented from occurring on the substrate when thefirst dividing groove and the second dividing groove are formed, and thefirst dividing groove and the second dividing groove can be formedaccurately at a constant depth.

Another feature of the present invention is configured as follows. Thedividing groove forming device further includes an X-direction driveunit for causing the first cutter and the second cutter to moverelatively to the substrate in a direction in which the first dividinggroove and the second dividing groove extend.

In this structure, the X-direction drive unit enables the first cutterand the second cutter to move relatively to the substrate. Therefore,the first dividing groove and the second dividing groove can be smoothlyformed.

Another feature of the present invention is configured as follows. Thefirst rotation drive unit includes a first motor, the second rotationdrive unit includes a second motor, the phase adjustment unit includes acontrol unit for controlling at least one of the first motor and thesecond motor, and the control unit controls at least one of the firstmotor and the second motor in such a manner that the first rotary bladesand the second rotary blades are opposed to each other in the opposingarea.

In this structure, at least one of the first motor and the second motoris controlled by the control unit. Therefore, the phase of at least oneof the first cutter and the second cutter can be adjusted rapidly andaccurately.

Another feature of the present invention is configured as follows. Theplurality of first rotary blades are the same in number as the pluralityof second rotary blades, and the plurality of first rotary blades andthe plurality of second rotary blades are provided at the same pitchangle, the phase adjustment unit includes a phase detection part fordetecting a phase of each of the first cutter and the second cutter, andthe control unit controls at least one of the first motor and the secondmotor in such a manner that a difference between the phase of the firstcutter and the phase of the second cutter is equal to an integralmultiple of the pitch angle.

In this structure, the plurality of first rotary blades are the same innumber as the plurality of second rotary blades, and the first rotaryblades and the second rotary blades are provided at the same pitchangle. Accordingly, the first rotary blades and the second rotary bladescan be opposed to each other in the opposing area, as long as adifference between the phase of the first cutter and the phase of thesecond cutter is equal to an integral multiple of the pitch angle.Therefore, the first rotary blades and the second rotary blades can beeasily opposed to each other in the opposing area only by controlling atleast one of the first motor and the second motor so that the phasedifference becomes equal to an integral multiple of the pitch angle.

In order to achieve the above-described object, a feature of a dividinggroove forming method according to the present invention is that thedividing groove forming method is for simultaneously forming a firstdividing groove and a second dividing groove for dividing a substrate atcorresponding positions on one surface and the other surface of thesubstrate, and the dividing groove forming method includes: (a)arranging a first cutter for forming the first dividing groove and asecond cutter for forming the second dividing groove in such a mannerthat the first cutter and the second cutter are radially opposed to eachother so that rotation axes of the first cutter and the second cutterare parallel to each other, the first cutter including a plurality offirst rotary blades, the second cutter including a plurality of secondrotary blades; (b) rotating the first cutter and the second cutter insuch a manner that the first rotary blades and the second rotary bladesare opposed to each other in an opposing area in which the first cutterand the second cutter are opposed to each other; and (c) forming thefirst dividing groove and the second dividing groove by causing thefirst cutter and the second cutter to move relatively to the substratein a direction in which the first dividing groove and the seconddividing groove extend.

In this method, the first rotary blades and the second rotary blades areopposed to each other in an opposing area in which the first cutter andthe second cutter are opposed to each other. Accordingly, a wavinessphenomenon can be prevented from occurring on the substrate when thefirst dividing groove and the second dividing groove are formed, and thefirst dividing groove and the second dividing groove can be formedaccurately at a constant depth.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view illustrating a structure of a dividing grooveforming device according to one embodiment of the present invention;

FIG. 2 is a block diagram illustrating the structure of the dividinggroove forming device according to one embodiment of the presentinvention;

FIG. 3 is a perspective view illustrating a process for forming adividing groove in a substrate;

FIG. 4 is an enlarged front view illustrating a state where first rotaryblades and second rotary blades are opposed to each other;

FIG. 5 is a flowchart illustrating each process of a dividing grooveforming method according to one embodiment of the present invention; and

FIG. 6 is a front view illustrating a positional relationship betweenfirst rotary blades and second rotary blades in a dividing grooveforming device of related art.

DESCRIPTION OF EMBODIMENTS

Embodiments of a dividing groove device and a dividing groove formingmethod according to the present invention will be described below withreference to the drawings.

[Dividing Groove Forming Device]

FIG. 1 is a front view illustrating a structure of a dividing grooveforming device 10 according to one embodiment of the present invention.FIG. 2 is a block diagram illustrating the structure of the dividinggroove forming device 10. FIG. 3 is a perspective view illustrating aprocess for forming dividing grooves 14 and 16 in a substrate 12. Asillustrated in FIG. 3, a direction in which the dividing grooves 14 and16 extend in a horizontal plane is hereinafter referred to as anX-direction; a vertical direction is hereinafter referred to as aZ-direction; and a direction perpendicular to each of the X-directionand the Z-direction is hereinafter referred to as a Y-direction.

As illustrated in FIG. 2, the dividing groove forming device 10 is usedto simultaneously form the first dividing groove 14 and the seconddividing groove 16 for dividing the substrate 12 at correspondingpositions on one surface 12 a and the other surface 12 b of thesubstrate 12. As illustrated in FIG. 3, the substrate 12 used in thisembodiment is a collective substrate which has a small thickness (athickness of about 0.3 to 0.4 mm) and in which a plurality of (nine inthis embodiment) unit substrates 18 that are used for an electric device(e.g., a cellular phone) and the like are built. The first dividinggroove 14 and the second dividing groove 16 have a depth of about 0.1 mmand are formed into a V-shape. Note that the thickness of the substrate12 and the depth of each of the first dividing groove 14 and the seconddividing groove 16 are not limited to those of this embodiment.

As illustrated in FIG. 1, the dividing groove forming device 10 includesa disk-shaped first cutter 20, a disk-shaped second cutter 22, arotating table 24, and a work chuck 26.

As illustrated in FIG. 1, the first cutter 20 includes a disk-shapedbase metal 30 and a plurality of (20 in this embodiment) first rotaryblades 32 which are provided at an outer periphery of the base metal 30.As illustrated in FIG. 2, a through-hole 36 through which a rotatingshaft 34 a of a first motor 34, which is described later, is inserted isformed at a central part of the base metal 30. In a part of the basemetal 30 in the vicinity of the through-hole 36, a plurality of (four inthis embodiment) through-holes 40 through which bolts 38 arerespectively inserted are formed. In a part of the base metal 30 in thevicinity of the through-holes 40, at least one (one in this embodiment)through-hole 44 through which a positioning pin 42 is inserted isformed.

The first rotary blades 32 illustrated in FIG. 1 are cutting blades forforming the first dividing groove 14 (FIG. 2) by cutting the substrate12. The plurality of first rotary blades 32 are provided at regularintervals (at angular intervals of 18 degrees in this embodiment) at theouter periphery of the base metal 30. In this embodiment, the firstcutter 20 is structured to rotate clockwise in a front view, and eachfirst rotary blade 32 is provided so as to face forward in the clockwisedirection.

As illustrated in FIG. 1, the second cutter 22 includes a disk-shapedbase metal 50 and a plurality of (20 in this embodiment) second rotaryblades 52 which are provided at an outer periphery of the base metal 50.As illustrated in FIG. 2, a through-hole 56 through which a rotatingshaft 54 a of a second motor 54, which is describer later, is insertedis formed at a central part of the base metal 50. In a part of the basemetal 50 in the vicinity of the through-hole 56, a plurality of (four inthis embodiment) through-holes 60 through which bolts 58 arerespectively inserted are formed. In a part of the base metal 50 in thevicinity of the through-holes 60, at least one (one in this embodiment)through-hole 64 through which a positioning pin 62 is inserted isformed.

The second rotary blades 52 illustrated in FIG. 1 are cutting blades forforming the second dividing groove 16 (FIG. 2) by cutting the substrate12. The plurality of second rotary blades 52 are provided at regularintervals (at angular intervals of 18 degrees in this embodiment) at theouter periphery of the base metal 50. In this embodiment, the secondcutter 22 is structured to rotate counterclockwise in a front view, andeach second rotary blade 52 is provided so as to face forward in thecounterclockwise direction.

As illustrated in FIG. 1, the rotating table 24 supports the substrate12 in the process for forming the first dividing groove 14 and thesecond dividing groove 16 (FIG. 2). The rotating table 24 is providedwith a table rotation drive unit 68 (FIG. 2) for changing the directionof the rotating table between the X-direction and the Y-direction.Accordingly, even when the substrate 12 supported by the rotating table24 is cut along a dividing line L1 and a dividing line L2, which areperpendicular to each other, the first cutter 20 and the second cutter22 may be caused to move only in one of the X-direction and theY-direction (only in the X-direction in this embodiment). The tablerotation drive unit 68 includes a servo motor (not shown). Asillustrated in FIG. 2, the table rotation drive unit 68 is electricallyconnected to a control unit 70. The servo motor (not shown) and the likeof the table rotation drive unit 68 are controlled based on a controlsignal supplied from the control unit 70.

As illustrated in FIG. 1, the work chuck 26 is used to fix the substrate12 to the rotating table 24. The work chuck 26 of this embodiment is avacuum chuck that is structured to be able to adsorb the substrate 12with a negative pressure. The work chuck 26 includes a solenoid valve(not shown) for switching an adsorbed state and an adsorption releasedstate. As illustrated in FIG. 2, the work chuck 26 is electricallyconnected to the control unit 70. The solenoid valve (not shown) and thelike of the work chuck 26 are controlled based on a control signalsupplied from the control unit 70.

As illustrated in FIG. 2, the dividing groove forming device 10 includesa first rotation drive unit 72, a second rotation drive unit 74, acutter support unit 76, an X-direction drive unit 80, a Y-directiondrive unit 82, and a phase adjustment unit 104.

As illustrated in FIG. 2, the first rotation drive unit 72 is a unit forrotationally driving the first cutter 20, and includes the first motor34 and a first motor driver 84. The first motor 34 of this embodiment isa servo motor and is structured to be rotationally driven at arotational speed of 8000 to 10000 rev/min. The rotating shaft 34 a ofthe first motor 34 is provided with a flange 86 to which the firstcutter 20 is fixed. The flange 86 is provided with screw holes 88 andthe positioning pin 42. The bolts 38 inserted through the through-hole40 of the first cutter 20 are threadedly engaged with the screw holes88, respectively. The positioning pin 42 is inserted through thethrough-hole 44 of the first cutter 20. In a state where the firstcutter 20 is fixed to the flange 86, the rotating shaft 34 a of thefirst motor 34 serves as the rotating shaft of the first cutter 20.

As illustrated in FIG. 2, the first motor 34 is provided with a firstphase detection part 90 for detecting the phase of the rotating shaft 34a (i.e., the phase of the first cutter 20). The first phase detectionpart 90 of this embodiment includes a rotary encoder. The first phasedetection part 90 and the control unit 70 are electrically connected toeach other.

The first motor driver 84 illustrated in FIG. 2 supplies a drive currentto the first motor 34. The first motor driver 84 is electricallyconnected to the control unit 70. When the control signal is supplied tothe first motor driver 84 from the control unit 70, the first motordriver 84 supplies a drive current corresponding to the control signalto the first motor 34.

As illustrated in FIG. 2, the second rotation drive unit 74 is a unitfor rotationally driving the second cutter 22 and includes the secondmotor 54 and a second motor driver 92. The second motor 54 of thisembodiment is a servo motor and is structured to be rotationally drivenat a rotational speed of 8000 to 10000 rev/min. The rotating shaft 54 aof the second motor 54 is provided with a flange 94 to which the secondcutter 22 is fixed. The flange 94 is provided with screw holes 96 andthe positioning pin 62. The bolts 58 inserted through the through-holes60 of the second cutter 22 are threadedly engaged with the screw holes96, respectively. The positioning pin 62 is inserted through thethrough-hole 64 of the second cutter 22. In a state where the secondcutter 22 is fixed to the flange 94, the rotating shaft 54 a of thesecond motor 54 serves as the rotating shaft of the second cutter 22.

As illustrated in FIG. 2, the second motor 54 is provided with a secondphase detection part 98 for detecting the phase of the rotating shaft 54a (i.e., the phase of the second cutter 22). The second phase detectionpart 98 of this embodiment includes a rotary encoder. The second phasedetection part 98 and the control unit 70 are electrically connected toeach other.

The second motor driver 92 illustrated in FIG. 2 supplies a drivecurrent to the second motor 54. The second motor driver 92 iselectrically connected to the control unit 70. When the control signalis supplied to the second motor driver 92 from the control unit 70, thesecond motor driver 92 supplies a drive current corresponding to thecontrol signal to the second motor 54.

As illustrated in FIG. 2, the cutter support unit 76 is a unit forsupporting the first cutter 20 and the second cutter 22 in such a mannerthat the first cutter 20 and the second cutter 22 are radially opposedto each other so that rotation axes of the first cutter 20 and thesecond cutter 22 are parallel to each other. The cutter support unit 76of this embodiment includes: the first motor 34 to which the firstcutter 20 is attached; the second motor 54 to which the second cutter 22is attached; a Z-direction drive unit 78 for supporting the first motor34 and the second motor 54; and a fulcrum 102 for supporting theZ-direction drive unit 78. The Z-direction drive unit 78 is a unit forcausing the first motor 34 and the second motor 54 to move in theZ-direction, and includes a linear guide and a servo motor (not shown).The Z-direction drive unit 78 is electrically connected to the controlunit 70. The servo motor (not shown) and the like of the Z-directiondrive unit 78 are controlled based on the control signal supplied fromthe control unit 70.

The X-direction drive unit 80 illustrated in FIG. 2 is a unit forcausing the first cutter 20 and the second cutter 22 to move in theX-direction together with the cutter support unit 76. The Y-directiondrive unit 82 illustrated in FIG. 2 is a unit for causing the firstcutter 20 and the second cutter 22 to move in the Y-direction togetherwith the cutter support unit 76. Each of the X-direction drive unit 80and the Y-direction drive unit 82 includes a linear guide and a servomotor (not shown). The X-direction drive unit 80 and the Y-directiondrive unit 82 are electrically connected to the control unit 70. Theservo motors (not shown) and the like of the X-direction drive unit 80and the Y-direction drive unit 82 are controlled based on the controlsignal supplied from the control unit 70.

FIG. 4 is an enlarged front view illustrating a state in which the firstrotary blades 32 and the second rotary blades 52 are opposed to eachother. The phase adjustment unit 104 illustrated in FIG. 2 is a unit foradjusting the phase of at least one of the first cutter 20 and thesecond cutter 22 in such a manner that the first rotary blades 32 andthe second rotary blades 52 are opposed to each other in an opposingarea Q (FIG. 4) in which the first cutter 20 and the second cutter 22are opposed to each other.

As illustrated in FIG. 2, the phase adjustment unit 104 of thisembodiment includes the first motor 34, the first phase detection part90, the first motor driver 84, the second motor 54, the second phasedetection part 98, the second motor driver 92, and the control unit 70.The control unit 70 includes a central processing unit (CPU) thatexecutes various arithmetic processes, and storage devices (ROM, RAM)for storing programs and data. The control unit 70 in the phaseadjustment unit 104 controls at least one of the first motor 34 and thesecond motor 54 for phase adjustment.

A reference line M illustrated in FIG. 4 is a virtual line that isperpendicular to the substrate 12 and passes through the rotation centerof the first cutter 20 and the rotation center of the second cutter 22.When the first phase detection part 90 and the second phase detectionpart 98 output a signal representing an origin position, the tip of eachof the first rotary blades 32 and the tip of each of the second rotaryblades 52 are disposed on the reference line M in the opposing area Q.

In this embodiment, the plurality of first rotary blades 32 are the samein number as the plurality of second rotary blades 52, and the pluralityof first rotary blades 32 and the plurality of second rotary blades 52are provided at the same pitch angle. Accordingly, the first rotaryblades 32 and the second rotary blades 52 can be opposed to each otherin the Z-direction in the opposing area Q, as long as the differencebetween the phase of the first cutter 20 and the phase of the secondcutter 22 is equal to an integral multiple of the pitch angle (18degrees in this embodiment). The control unit 70 illustrated in FIG. 2controls at least one of the first motor 34 and the second motor 54 insuch a manner that the phase difference is equal to an integral multipleof the pitch angle (18 degrees in this embodiment).

[Dividing Groove Forming Method]

When the first dividing groove 14 and the second dividing groove 16 areformed in the substrate 12 along the dividing lines L1 and L2illustrated in FIG. 3, the substrate 12 is first placed on the rotatingtable 24 illustrated in FIG. 1, and the substrate 12 is fixed by thework chuck 26. Subsequently, the first dividing groove 14 and the seconddividing groove 16 are formed along each dividing line L1 (FIG. 3) byrotationally driving the first cutter 20 and the second cutter 22 tomove in the X-direction and the Y-direction.

When the operation for forming the first dividing groove 14 and thesecond dividing groove 16 along a plurality of dividing lines L1illustrated in FIG. 3 is completed, the rotating table 24 illustrated inFIG. 1 is rotated to change the direction in which each dividing line L2(FIG. 3) of the substrate 12 extends, from the Y-direction to theX-direction. After that, the first dividing groove 14 and the seconddividing groove 16 are formed along each dividing line L2 (FIG. 3) bymoving the first cutter 20 and the second cutter 22 in the X-directionand the Y-direction. Note that an alternate long and two short dashesline illustrated in FIG. 3 indicates the state of the substrate 12 afterthe direction is changed.

A method for forming the first dividing groove 14 and the seconddividing groove 16 along the dividing lines L1 and L2 (dividing grooveforming method) will be described in detail below with reference to theflowchart of FIG. 5.

When the control unit 70 illustrated in FIG. 2 starts a dividing grooveforming program, the control unit 70 executes steps S1 to S7 illustratedin FIG. 5 in this order. First, in step S1, the control unit 70 controlsthe first motor 34 and the second motor 54 to rotationally drive thefirst cutter 20 and the second cutter 22. At this time, the first cutter20 and the second cutter 22 are separated from each other in theZ-direction by the Z-direction drive unit 78.

During the formation of the first dividing groove 14 and the seconddividing groove 16, if the positions of the first rotary blades 32 andthe second rotary blades 52 deviate in the X-direction in the opposingarea Q illustrated in FIG. 4, a waviness phenomenon occurs on thesubstrate 12, so that the depth of each of the first dividing groove 14and the second dividing groove 16 becomes non-uniform. Accordingly, insteps S2 and S3, the control unit 70 of the phase adjustment unit 104illustrated in FIG. 2, the phase of the second cutter 22 is adjusted insuch a manner that the first rotary blades 32 and the second rotaryblades 52 are opposed to each other.

Specifically, in step S2, the control unit 70 acquires the phases of thefirst cutter 20 and the second cutter 22 that are detected by the firstphase detection part 90 and the second phase detection part 98 (FIG. 2),respectively. In step S3, the control unit 70 adjusts the phase of thesecond cutter 22 by controlling the second motor 54 (FIG. 2) in such amanner that the first rotary blades 32 and the second rotary blades 52are opposed to each other in the opposing area Q (FIG. 4). The controlunit 70 continuously performs the processes of steps S2 and S3 until thedividing groove forming program is completed. Note that in step S3, thecontrol unit 70 may control the first motor 34 (FIG. 2) to adjust thephase of the second cutter 22. Further, the control unit 70 may adjustthe phases of the first cutter 20 and the second cutter 22 bycontrolling both the first motor 34 and the second motor 54 (FIG. 2).

In step S4, the control unit 70 controls the X-direction drive unit 80,the Y-direction drive unit 82, and the Z-direction drive unit 78 tothereby position the first cutter 20 and the second cutter 22 to astarting point P1 illustrated in FIG. 3. At this time, the Z-directiondrive unit 78 moves the first cutter 20 and the second cutter 22 indirections approaching each other. In step S5, the control unit 70controls the X-direction drive unit 80 to move the first cutter 20 andthe second cutter 22 in the X-direction, thereby forming the firstdividing groove 14 and the second dividing groove 16 in the substrate12.

In step S6, the control unit 70 determines whether or not the firstcutter 20 and the second cutter 22 have reached an end point P2 (FIG. 3)in the X-direction. When the control unit 70 determines that the firstand second cutters have not reached the end point, the control unit 70continues the operation of step S5 (movement in the X-direction). Whenthe control unit 70 determines that the first and second cutters havereached the end point, the control unit proceeds to step S7. Whether ornot the first cutter 20 and the second cutter 22 have reached the endpoint P2 can be determined based on, for example, an output of a limitswitch (not shown) that is pressed by the cutter support unit 76 (FIG.2).

In step S7, the control unit 70 controls the X-direction drive unit 80,the Y-direction drive unit 82, and the Z-direction drive unit 78 (FIG.2), thereby moving the first cutter 20 and the second cutter 22 to thenext starting point. Thus, the process for forming the first dividinggroove 14 and the second dividing groove 16 along one of the pluralityof dividing lines L1 and one of the plurality of dividing lines L2 isfinished.

Advantageous Effects of Embodiments

According to this embodiment, the following advantageous effects can beprovided by the structure described above. That is, as illustrated inFIG. 4, the first rotary blades 32 and the second rotary blades 52 areopposed to each other in the opposing area Q in which the first cutter20 and the second cutter 22 are opposed to each other. This structureprevents a waviness phenomenon from occurring on the substrate 12.Accordingly, the first dividing groove 14 and the second dividing groove16 (FIG. 2) can be formed accurately at a constant depth.

The X-direction drive unit 80 illustrated in FIG. 2 can cause the firstcutter 20 and the second cutter 22 to move relatively to the substrate12. Accordingly, the first dividing groove 14 and the second dividinggroove 16 can be smoothly formed. Further, the first motor 34 and thesecond motor 54 are controlled by the control unit 70. Therefore, thephase of at least one of the first cutter 20 and the second cutter 22can be adjusted rapidly and accurately.

As illustrated in FIG. 1, the plurality of first rotary blades 32 arethe same in number as the plurality of second rotary blades 52, and theplurality of first rotary blades 32 and the plurality of second rotaryblades 52 are provided at the same pitch angle. Accordingly, the firstrotary blades 32 and the second rotary blades 52 can be easily opposedto each other only by controlling at least one of the first motor 34 andthe second motor 54 so that the phase difference is equal to an integralmultiple of the pitch angle.

Modified Examples

Note that the implementation of the present invention is not limited tothe above embodiments and can be modified in various ways withoutdeparting from the scope of the present invention. For example, asillustrated in FIG. 3, in the above embodiments, the first cutter 20 andthe second cutter 22 are moved in the X-direction relatively to thesubstrate 12. On the contrary, the substrate 12 may be moved (not shown)in the X-direction relatively to the first cutter 20 and the secondcutter 22.

Further, as illustrated in FIG. 2, in the above embodiments, the phaseadjustment unit 104 including the control unit 70 is used as a phaseadjustment unit for adjusting the phase of at least one of the firstcutter 20 and the second cutter 22. Alternatively, a mechanical phaseadjustment unit (not shown) composed of a gear, a timing belt, or thelike may be used.

DESCRIPTION OF REFERENCE SIGNS

-   10 Dividing groove forming device-   20 First cutter-   22 Second cutter-   32 First rotary blade-   52 Second rotary blade-   72 First rotation drive unit-   74 Second rotation drive unit-   76 Cutter support unit-   104 Phase adjustment unit

1. A dividing groove forming device for simultaneously forming a firstdividing groove and a second dividing groove for dividing a substrate,the first dividing groove and the second dividing groove beingrespectively formed at corresponding positions on one surface and theother surface of the substrate, the dividing groove forming devicecomprising: a first cutter for forming the first dividing groove, thefirst cutter including a plurality of first rotary blades; a secondcutter for forming the second dividing groove, the second cutterincluding a plurality of second rotary blades; a first rotation driveunit for rotationally driving the first cutter; a second rotation driveunit for rotationally driving the second cutter; a cutter support unitfor supporting the first cutter and the second cutter in such a mannerthat the first cutter and the second cutter are radially opposed to eachother so that rotation axes of the first cutter and the second cutterare parallel to each other; and a phase adjustment unit for adjusting aphase of at least one of the first cutter and the second cutter in sucha manner that the first rotary blades and the second rotary blades areopposed to each other in an opposing area in which the first cutter andthe second cutter are opposed to each other.
 2. The dividing grooveforming device according to claim 1, further comprising an X-directiondrive unit for causing the first cutter and the second cutter to moverelatively to the substrate in a direction in which the first dividinggroove and the second dividing groove extend.
 3. The dividing grooveforming device according to claim 1, wherein the first rotation driveunit includes a first motor, the second rotation drive unit includes asecond motor, the phase adjustment unit includes a control unit forcontrolling at least one of the first motor and the second motor, andthe control unit controls at least one of the first motor and the secondmotor in such a manner that the first rotary blades and the secondrotary blades are opposed to each other in the opposing area.
 4. Thedividing groove forming device according to claim 3, wherein theplurality of first rotary blades are the same in number as the pluralityof second rotary blades, and the plurality of first rotary blades andthe plurality of second rotary blades are provided at the same pitchangle, the phase adjustment unit includes a phase detection part fordetecting a phase of each of the first cutter and the second cutter, andthe control unit controls at least one of the first motor and the secondmotor in such a manner that a difference between the phase of the firstcutter and the phase of the second cutter is equal to an integralmultiple of the pitch angle.
 5. A dividing groove forming method forsimultaneously forming a first dividing groove and a second dividinggroove for dividing a substrate at corresponding positions on onesurface and the other surface of the substrate, the dividing grooveforming method comprising: (a) arranging a first cutter for forming thefirst dividing groove and a second cutter for forming the seconddividing groove in such a manner that the first cutter and the secondcutter are radially opposed to each other so that rotation axes of thefirst cutter and the second cutter are parallel to each other, the firstcutter including a plurality of first rotary blades, the second cutterincluding a plurality of second rotary blades; (b) rotating the firstcutter and the second cutter in such a manner that the first rotaryblades and the second rotary blades are opposed to each other in anopposing area in which the first cutter and the second cutter areopposed to each other; and (c) forming the first dividing groove and thesecond dividing groove by causing the first cutter and the second cutterto move relatively to the substrate in a direction in which the firstdividing groove and the second dividing groove extend.
 6. The dividinggroove forming device according to claim 2, wherein the first rotationdrive unit includes a first motor, the second rotation drive unitincludes a second motor, the phase adjustment unit includes a controlunit for controlling at least one of the first motor and the secondmotor, and the control unit controls at least one of the first motor andthe second motor in such a manner that the first rotary blades and thesecond rotary blades are opposed to each other in the opposing area. 7.The dividing groove forming device according to claim 6, wherein theplurality of first rotary blades are the same in number as the pluralityof second rotary blades, and the plurality of first rotary blades andthe plurality of second rotary blades are provided at the same pitchangle, the phase adjustment unit includes a phase detection part fordetecting a phase of each of the first cutter and the second cutter, andthe control unit controls at least one of the first motor and the secondmotor in such a manner that a difference between the phase of the firstcutter and the phase of the second cutter is equal to an integralmultiple of the pitch angle.